It has long been the practice to make up a drill string from threaded drill stem sections having a pin joint at one end and a box joint at the other end, and such drill string has been used not only in drilling oil wells but also in mining and in other applications. As the drilling advances it is necessary to add one drill stem section at a time in order to lengthen the drill string, and when the tool is being removed from the hole the drill stem sections are broken out one at a time. The procedure for adding or breaking out a drill stem section has been both time-consuming and expensive, since the drill string as a whole as well as the individual drill stem section must be separately supported each time that the threaded joint between them is made or broken and a number of separate steps have heretofore been required in the handling of the individual drill stem section.
The copending application Ser. No. 551,083 discloses a boring machine for drilling upwardly, and a novel method or process for adding or breaking out the drill stem sections which is more fully automated than the previously known methods. The drill stem of the present invention is particularly adapted for carrying out that novel method.